Power-amplifying system



April 10, 1928. 1,665,883

E. w. KELLOGG POWER AMPLIFYING SYSTEM Filed May 13.- 1926 lhventor Edward W Ke I logzg His Attorney.

'Patented Apr. 10, 1928.

: UNITED STATES- 1,665,883 PATENT OFFICE";

EDWARD W. KELLOGG, OF SGHENECTADY, NEW YORK, ASSIGNOR T GENERAL ELEC- TRIO COMPANY, A. CORPORATION OF NEW YORK.

POWEIt-AMPLIFYING- SYSTEM. 7

Application filed May 13,

My invention relates to systems for emplifying power, and has for its prlncipal object the provision of'a push-pull amplifylng system which is readlly adjusted to p cause equal voltages to be applied to its two case the arallel connection involves the loss of consi erable power in the resistors, but the parallel connection of the filaments has been used heretofore because the connection of the filaments or cathode heating circuits in series with one another produces unba1- .ance in the volta es applied to the dliferent units of the amp ifier f the usual input and output transformers having'mid-pomt taps are used. In accordance with my invention, these difiiculties are avoided by provldmg each input circuit of the push-pull amplifier with a separate connection and appllyingthe 3 required potentials to the 1nput,cat odeheating and output circuits through an impedance device connected to a suitable source of current.

y from the following descri tion when considered in connection with t e accompanylng drawings and its scope will be pointed out in the appended claims.

Referring to the drawings, Fig. 1 shows an amplifying system wherein my invention has been embodied; and Fig. 2 shows this system provided with-an additional stage of ampl fication.

Fig. 1 shows a push-pull amplifier comrising thermionic devices 1 and 2 which iiave their cathode heating and output circuits connected to a direct current supply circuit 3 through an impedance device comprising sections or elements 4 to 7. The thermlonic device 1 comprises a cathode 8 which is connected across the section 5 of the impedance device, an anode 9 which is connected to the positive side of the line 3 through a primary circuit 10 of an output transformer 11 and an adjustable portion of the invention will be better understood.

1926. Serial No. 108,941.

section 4 of the impedance device, and a grid 12 which is connected to the cathode 8 through a secondary circuit 13 of an input transformer 14, a part of section 7 of the impedance device and all of section 6 of th s device. The thermionic device 2 comprises a cathode 15 which is connected across the section 6 of the impedance device, an anode 16 which is connected to the positive side of the line 3 through a primary circuit 17 of the output transformer 11 and an adustable ortion of the section 4 of the impedance evice, and a grid 18 which is connected to the cathode 15 through a second- I Y ary circuit 19 of the input transformer 14 and section 7 of the impedance device.

The currents to be amplified are supplied to a primary circuit 20 of the input transformer 14 and the amplified currents are supplied through a secondary circuit 21 of the output transformer 11 to a translating device 22. In the drawings, this translating dev ce is shown as a sound producing device provided with an operating coil 23 connected to the secondary winding 21 and with a field or choke coil 24 connected to the dircult 3 in series with the impedance device. The field or choke coil 24 of the device 22 may be connected to the impedance device between the adjustable plate taps and the cathodes where the voltage of the circuit 3 is not sufiiciently high to permit of its connection in the manner illustrated.

It should be noted that the connection of 'the cathodes-across sections of the impedtheir respective taps along the section 4 of the impedance device, and that the connections of the grids 12 and 18 to the section 7 of the impedance device will be so made or adjusted as to ensure that equal bias voltages are applied to the grid circuits.

Fig.2 shows an amplifying system'which' differs from that of Fig.1 in that the ourrents to be amplified are supplied to the push-pull amplifier through a transformer 25 and a thermionic amplifier 26 which is operated by current supplied through the impedance device from the circuit 3.

The embodiments of the invention illustrated and described herein have been selected for the purpose of clearly setting forth the principles involved. It will be apparent however, that the invention is susceptibie of being modified to meet the different conditions encountered in its use and I therefore aim to cover by the appended claims all modifications within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The combination of direct current supply means, a push-pull amplifier provided with cathode heating circuits connected to said supply means in series with one another, and means arranged to cause equal parts of the voltage of said supply means to be applied to the output circuits of said amplifiers.

2. The combination of direct current supply means, a push-pull amplifier provided with cathode heating circuits connected to said supply means in series with one another, means arranged to cause equal parts of the voltage of said supply means to be applied to the output circuits of said amplifiers, and separate circuits for energizing the input circuits of said amplifier.

3. The combination of direct current supply means, a push-pull amplifier provided with cathode heating circuits connected to said supply means in series with one another, means arranged to cause equal parts of the voltage of said supply means to be applied to the output circuits of said amplifiers, and a transformer provided with separate secondary circuits each connected to a difl'erent input circuit of said amplifier.

4. The combination of current supply means, impedance means connected to said supply means, and a push-pull amplifier provided with cathode heating circuits connected across different portions of said impedance means and with output circuits connected across portions of sald impedance means that have equal potential drops.

5. The combination of current supply means, impedance means connected to said supp y means, a ush-pull amplifier provided wit cathode eating circuits connected across diiferent portions of said impedance means and with output circuits connected across portions of said impedance means that have equal potential drops, and separate circuits connected to the different input circuits of said' amplifier through substantially equal portions of said impedance means.

6. The combination of current supply means, impedance means connected to said supply means, a push-pull amplifier provided with cathode heating circuits connected across different portions of said impedance means andwith output circuits connected to said impedance means through means for adjusting the connections to said output circuits to cause equal voltages to be applied thereto throu h said impedance means.

7 The comfiination of direct current supply means, a push-pull amplifier provided with cathode heating circuits connected to said supply means in series with one another, means connected to said supply means in series with said cathode circuits for causing equal voltages to be applied to the output circuits of said am lifier.

8. The combination of a direct current sup ply circuit, a push-pull amplifier provided with cathode heating circuits connected to said supply circuit in series with one another, means connected to said supply means in series with said cathode circuits for causing equal voltages to be applied to the output circuits of said amplifier, and a translating device provided with one coil connected to said supply circuit in series with said means andcathode heating circuits and with another coil interconnected with said output circuits.

9. The combination of a direct current supply circuit, a push-pull amplifier provided with cathode heating circuits connected to said supply means in series with one another, means connected to said supply means in series with said cathode circuits for causing equal voltages to be applied to the output circuits of said amplifier, and means connected in shunt to said cathode heatin circuits for equalizing the currents thereo In witness whereof. I have hereunto set my hand this 11th day of May, 1926.

EDWARD W. KELLOGG. 

